Sweat collecting device

ABSTRACT

A sweat collection device includes an elongate concave sweat-collecting surface at a face thereof for placement over an iontophoresis-stimulated area of a patient&#39;s skin to collect sweat and pass it through an axial bore in the concavity. A length of flexible tubing is secured to the axial bore for receiving and storing the collected sweat. A chamber may be provided for holding the tubing in flat coiled condition. Collected sweat builds up within the tubing from the axial bore. The device can include markings to indicate when a minimum amount of sweat has been collected in the tubing and can indicated a range for collected sweat that takes into account variations in the tubing. An open end of the tubing can be flared for easy insertion of a blunt needle to extract sweat or a guide passage can guide insertion of the needle into the open end of the tubing.

RELATED APPLICATIONS

This is a continuation-in-part of application Ser. No. 13/841,296, filedMar. 15, 2013, entitled Sweat Collecting Device, incorporated herein inits entirety by reference.

BACKGROUND

Field of the Invention

The present invention relates generally to the collection of human sweatfor medical evaluation and is particularly directed to sweat collectiondevices.

Related Art

It is known that the concentrations of sodium and chloride areconsiderably above normal in the sweat of individuals suffering fromcystic fibrosis. Sweat testing is routinely used to diagnose cysticfibrosis, particularly in infants, where such testing is often donebetween birth and about four weeks of age. In one method of sweatcollection, as described in U.S. Pat. No. 4,542,751, incorporated hereinby reference, sweating is induced in a substantially flat area of skinby pilocarpine iontophoresis, usually performed using an electrode witha substantially circular pilocarpine containing gel disc, as describedin U.S. Pat. No. 4,383,529, incorporated herein by reference, and asmanufactured by Wescor, Inc. of Logan, Utah, as a Pilogel® IontophoresisDisc, placed over the skin of the individual to be tested where sweatingis desired. A return electrode is placed on the skin near the electrodewith the pilocarpine containing gel disc and a voltage is appliedbetween the electrodes sufficient to cause current flow through thepilocarpine containing gel disc and into the skin between theelectrodes. The pilocarpine molecules flow from the pilocarpinecontaining gel disc through and into the skin area in contact with thepilocarpine containing gel disc. When the pilocarpine iontophoresis iscomplete, the electrodes are removed. The pilocarpine in the circularskin area that was under and in contact with the circular pilocarpinecontaining gel disc activate the sweat glands in that skin area so thatsweating takes place in that skin area.

After removal of the electrodes, a sweat collecting device known as theMacroduct® Sweat Collector, manufactured by Wescor, Inc. of Logan, Utah,which has a concave underside sweat-collecting surface of circular crosssection, is placed over the iontophoretically-stimulated area on theskin and the device is firmly strapped in place. Sweat secreted by theindividual's sweat glands flows between the skin and the concaveunderside sweat-collecting surface of the sweat collector and into amicro bore sweat collector tube. After a sufficient volume of sweat hasaccumulated in the sweat collector tube, the sweat is expelled from thetube and tested for chloride, sodium, and/or total electrolyte content.

While the prior art Macroduct® Sweat Collector described in the abovereferenced U.S. Pat. No. 4,542,751 works well in collecting sweat frominfants for most testing currently being done, producing and collectingenough sweat for some testing is sometimes a problem. Sweat for sweattesting is usually collected from the arm or leg of the patient beingtested. Because of the small width of an infant's arm or leg,particularly when four weeks or less of age, the diameter, and thereforethe cross sectional area, of the circular cross section of theiontophoresis creating electrode and the circular cross section of thesweat-collecting surface of the sweat collector are limited by the widthof the arm or leg. This limits the size of the area of the infant fromwhich sweat can be produced and then collected by the sweat collector.

SUMMARY OF THE INVENTION

It has been found that by elongating the circular cross section of theconcave underside sweat-collecting surface of the Macroduct® SweatCollector, the sweat-collecting surface of the sweat collector will havea larger overall cross sectional area to thereby collect more sweat in agiven period of time than does the prior art circular cross sectionconcave undersurface and will still fit the geometry of small limbs ofinfants. By elongating the circular cross section of the concaveunderside sweat-collecting surface, the width of the sweat-collectingsurface is not increased so as to still fit within the width of theinfant's arm or leg, while the length of the sweat-collecting surfacealong the length of the arm or leg is increased, but since the length ofthe arm or leg is normally greater than the width of the arm or leg,will still comfortably fit on a substantially flat portion of the arm orleg. However, increasing the cross sectional area of thesweat-collecting surface of the sweat collector will increase the amountof sweat collected only if sweat is being produced by the increased areaof the skin covered by the increased area of the sweat-collectingsurface. Therefore, when a pilocarpine iontophoresis system is beingused to produce the area of sweating, such system has to producesweating in the increased area of sweat collection. If the pilocarpineiontophoresis system of the referenced U.S. Pat. No. 4,383,529 is usedin conjunction with the sweat collector of the invention, the electrodewith the pilocarpine containing gel disc and the pilocarpine containinggel disc used should have an elongated cross sectional configuration andarea at least about equal to the elongated cross sectional configurationand area of the sweat-collecting surface of the sweat collector. Whenusing a sweat collector with the elongated sweat-collecting surface, asimilarly elongated pilocarpine containing disc will be used for thepilocarpine iontophoresis so that sweating is induced in substantiallyall of the skin covered by the sweat-collecting surface of the sweatcollector.

Thus, according to the invention, a sweat collection device forapplication to a substantially flat area of the human body comprises asolid body having a face thereof forming an elongate concavesweat-collecting surface which gradually recedes from a rim lying whollyin a common plane to an axial bore that extends to the opposite face ofthe solid body, the maximum depth of the concave means being such thatthe skin and flesh of the flat area of a human body to which the deviceis applied will bulge into contact with the sweat-collecting surfaceover substantially the entire area thereof when the rim is placed firmlyagainst the skin of the flat area of the human body, leavingsubstantially no dead space in the interface between the bulged skin andthe sweat-collecting surface, whereby body secretion pressure of sweatwill force the sweat along the sweat-collecting surface to and throughthe axial bore. The axial bore is adapted to connect with a length offlexible, sweat collector tubing at the opposite face of the solid body,and the solid body is adapted to be fastened against the flat area of ahuman body from which sweat is to be collected so as to maintain firmplacement of said rim and sweat-collecting surface against the skin. Therim may be elliptical in circumference to form an elliptical shapedsweat-collecting surface

In further improving the prior art device, the free open end of thesweat collector tubing may be flared to more easily receive a smallsyringe or blunt needle for use in removal of sweat from the sweatcollector tubing. Alternately, a guide passage may be provided in thesweat collector body to extend through the body from the chamber forreceiving the flexible sweat collector tubing to outside the sweatcollector body. The entrance to the guide passage from outside the bodyprovides a guide opening to receive the end of a small syringe or bluntneedle and the guide passage will guide the end of the syringe or needleinto the open end of the sweat collector tubing. The guide opening canbe tapered to more easily receive the end of the syringe or needletherein.

Further, since the inside diameter of the sweat collector tubing whichis usually formed by extrusion is subject to small variations within themanufacturing tolerance for the tubing, the volume of sweat collectedwithin a fixed length of the tubing is subject to small variations.Therefore, the collector tubing or device holding the collector tubingmay be marked to indicate when sufficient sweat has been collected forthe desired testing. Such indication, in addition to indicating when asufficient amount of sweat has definitely been collected taking intoaccount the potential variations in the extruded cross sectional area ofthe tubing, can also identify the range of volume of sweat collected inthe collector tube that, taking into account the potential variations inthe extruded cross sectional area of such tubing, may be sufficient fortesting, or may not be sufficient for testing.

In addition, an improved system for strapping the sweat-collectingdevice in place against the skin of a person from whom sweat is to becollected provides a stretchable strap, such as an elastic strap, theends of which are passed through strap receiving slots in the body ofthe device and are then doubled back and positioned so that a projectionassociated with each slot extends through a selected receiving hole of aplurality of receiving holes in the end portion of the strap. Inselecting the receiving hole in the strap through which the projectionis passed, the strap is stretched to a desired extent to provide adesired tightness of the device against the person's skin. Theprojections can extend outwardly from opposite sides of the body alignedwith the grooves so the ends of the strap can be easily positionedaround a respective projection.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional features and advantages of the invention will be apparentfrom the detailed description which follows, taken in conjunction withthe accompanying drawings, which together illustrate, by way of example,features of the invention; and, wherein:

FIG. 1, is a pictorial view of the sweat collecting device of theinvention showing the device secured to the forearm, shown fragmentarilyin broken lines, of a patient;

FIG. 2, a top plan view of the device of FIG. 1;

FIG. 3, a vertical section taken on the line 3-3 of FIG. 2;

FIG. 4, a bottom plan view of the device of FIG. 1;

FIG. 5, a fragmentary top plan view of the lower right hand portion ofthe receiving recess for the sweat collector tubing in the sweatcollecting device showing sweat collector tubing coiled therein, andshowing markings on the sweat collector tubing to show a range of volumeof sweat collected in the sweat collector tubing;

FIG. 6, a fragmentary top plan view of the lower right hand portion ofthe receiving recess for the sweat collector tubing in the sweatcollector device showing sweat collector tubing coiled therein similarto FIG. 5, but showing markings on the sweat collector body to show arange of volume of sweat collected in the sweat collector tubing;

FIG. 7, a fragmentary top plan view of the lower right hand portion ofthe receiving recess for the sweat collector tubing in the sweatcollector device showing sweat collector tubing coiled therein similarto FIG. 5, but showing markings on a cover over the receiving recess toshow a range of volume of sweat collected in the sweat collector tubing;

FIG. 8, a fragmentary longitudinal section of the open end portion ofthe sweat collector tubing showing how the open end of the sweatcollector tubing may be flared for easy insertion of a small syringe orblunt needle for use in removal of sweat from the collector tubing;

FIG. 9, a fragmentary longitudinal section of the open end portion ofthe sweat collector tubing similar to that of FIG. 8 showing an insertin the open end of the sweat collector tubing providing the flare foreasy insertion of a small syringe or blunt needle;

FIG. 10, a pictorial view of a further embodiment of the sweatcollecting device of the invention including a guide passage extendingfrom the open end of the sweat collector tubing positioned in the deviceto the outside of the device for guiding the end of a small syringe orblunt needle into the end of the sweat collector tubing, and showing aslightly different shape for the body of the device;

FIG. 11, a pictorial view, similar to that of FIG. 1, of a furtherembodiment of a sweat collecting device of the invention secured to theforearm, shown fragmentarily in broken lines, of a patient, and showinga different device configuration and attachment arrangement to the arm;and

FIG. 12, a fragmentary view of the slot and perimeter edge of thebacking plate as shown in FIG. 11 in line with FIG. 12, but without thestrap attached thereto.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the illustrated example embodiment as shown in FIGS. 1-4, similarlyto the sweat collector shown in referenced prior art U.S. Pat. No.4,542,751, the device of the invention comprises a sweat collector body9 advantageously molded to shape from a suitable plastic material, suchas polyethylene or polystyrene, and including a sweat collecting portion10 projecting integrally from a back portion formed as a backing plate11 provided with slot-like openings 12 at opposite sides thereof for thereception of straps 16 constituting means for attaching the device to aperson. However, sweat collecting portion 10 projecting integrally frombacking plate 11, rather than being of disc formation as in U.S. Pat.No. 4,542,751, is of elongate formation with the axis of elongationbeing substantially parallel to the slot-like openings 12.

The face of sweat collecting portion 10 has a shallow concavity 13 whoserim 14 lies wholly in a common plane and which is defined by a broad,sweat-collecting, concave surface 15. Concavity 13 is of squatformation, having a broad base and very short altitude. Rim 14 ofconcavity 13 may include a flat peripheral width around the concavesurface 15 or may merely be the edge of the concave sweat-collectingsurface 15.

Such concave face of sweat-collecting portion 10 is adapted to be placedand held firmly against the surface of a patient's skin by asize-adjustable strap 16, whose ends are secured in slots 12. A coiledlength of flexible, sweat-collector tubing 17 is shown as having one ofits ends fitted into or otherwise connected to an axial bore 18, whichextends axially through the body portion 10 and communicates withconcavity 13 at the apex of concave, sweat-collecting surface 15. Theother end of sweat-collector tubing 17 is normally open to allow air toescape as sweat flows into the tubing.

In the illustrated embodiment, provision is made for retention ofsweat-collector tubing 17 in compactly coiled form in the back of thesweat collector body 9 by recessing backing plate portion 11 in the formof a circular receiving chamber 19 overlying a portion ofsweat-collecting surface 15. Sweat collector tubing 17 is coiled in flatspiral formation and placed in the receiving chamber 19.

Sweat is generally collected from the fleshy underside of a patient'sforearm or from the fleshy portion of the patient's inner thigh. FIG. 1shows the sweat collector secured to a patient's forearm 20. Forconvenient application to the limb, strap 16 is can be provided as twoseparate lengths with means for adjustment, such as by having matingpieces of hook and loop fastener material, such as “Velcro”, applied tooverlapping ends thereof. When the device is in place on a patient'sskin, the skin and underlying flesh bulge into the concavity 13 againstsweat-collecting surface 15.

Prior to placing the device on a patient's skin, the skin over which thedevice is to be placed is treated to induce sweat production. Thistreatment will usually be with an iontophoretic electrode, i.e., anelectrode containing an ionic drug source, such as pilocarpine, placedagainst the skin to be treated, with a second return electrode placedagainst the skin near the iontophoretic electrode so that when a voltageis applied between the electrodes, a current will pass through the skinbetween the electrodes causing the ionic pilocarpine drug molecules tomigrate through the skin in contact with the iontophoretic electrode.Such an iontophoretic electrode may be as shown in referenced prior artU.S. Pat. No. 4,383,529 with the ionic drug source being a pilocarpinecontaining gel disc as disclosed in that patent. After iontophoresis iscompleted, the electrodes are removed and the concave sweat-collectingsurface 15 of the sweat collecting device is placed over the skin wherethe iontophoretic electrode had been. The pilocarpine under the skinstimulates the sweat glands to produce sweat for an extended period oftime which sweat is then collected by the sweat collecting device.However, for use with the sweat collecting device of the currentinvention, the iontophoretic electrode including the preformedpilocarpine containing gel disc will have substantially the sameelongated shape and size as the shape and size of the elongatedsweat-collecting surface of the sweat collecting device of the currentinvention.

The concavity 13 backed by the concave, sweat-collecting surface 15 isso shallow as to place the area of skin covered thereby in contact withthe sweat-collecting surface 15 over substantially the entire area ofthe sweat-collecting surface 15 without leaving dead space. In this way,sweat, under the pressure at which it is secreted from the sweat glands,is able to rapidly travel across the interface of the skin andcollecting surface 15 toward, into, and through axial bore 18, so thatsubstantially all of the sweat is collected in the flexiblesweat-collector tubing 17. Pressure of the collecting surface and rim ofthe device against the skin should be only that which will effect firmplacement against the skin. Excessive tightening of strap 16 is neithernecessary nor desirable. Four symmetrically positioned, relatively shortand outwardly tapered, radial ribs 22 formed integrally with sweatcollector body 9 protrude into concavity 13 as barriers to soft skin andflesh blocking the entrance to axial bore 18. Rather than protrudingribs, recesses could be similarly provided for the same purpose.

In the embodiment illustrated, a maximum width of the elongate open baseof concavity 13 of twenty-seven (27) millimeters and length of aboutforty (40) millimeters, with a depth of about one (1) millimeter at theapex, i.e. for the altitude of the elongate squat formation, has beenfound to be satisfactory, along with collector tubing 17 having aninside diameter of about 0.86 millimeters. While these measurements aresatisfactory, the measurements can vary. For example, the concavitycould have a depth or altitude substantially in the range of from aboutone-half (0.5) millimeter to about one and three-quarters (1.75)millimeters, a width substantially in the range of about fifteen (15)millimeters to about thirty five (35) millimeters, and a lengthsubstantially in the range of about twenty (20) millimeters to aboutseventy (70) millimeters, with a length-to-width ratio from about oneand three-tenths (1.3) to about two (2). The important considerations indetermining dimensions are that the depth or altitude should be smallenough to prevent significant dead space between the sweat-collectingsurface and the bulged skin, that the width is small enough to fit thewidth of the limb of the expected patient, such as a new born infantbetween birth and about four weeks of age, and the length is greatenough to provide a sweat-collecting surface area that, in most cases,will easily produce enough sweat for valid sweat testing within the timeof expected induced sweat production, usual no more than about thirtyminutes. While various elongated shapes can be used, it is believed thata shape having curved rather than straight lines, such as an ellipticalshape, will provide better sealing around the rim of thesweat-collecting surface.

In use of the device having the example dimensions indicated above, ithas been found that about one minute elapses from the time the device isstrapped onto an area of the patient's skin that has been stimulated byiontophoretic application of pilocarpine, until sweat appears incollector tubing 17. Once sweat appears, it is possible to see themeniscus of sweat advance in the tubing. If desired, markings may beprovided to indicate the approximate volume of sweat collected. However,since the inside diameter of the sweat collector tubing which is usuallyformed by extrusion is subject to small variations within themanufacturing tolerance for the tubing, the volume of sweat collectedwithin a fixed length of the tubing is subject to small variations.Therefore, it is not usually possible to provide a mark on the tubingthat will indicate the volume of sweat actually collected within theaccuracy required for sweat testing for cystic fibrosis within thestandards of the Cystic Fibrosis Foundation. The volume of sweat testedfrom the volume of sweat collected will need to be measured by moreaccurate means, such as by weighing. However, the sweat collector tubingor the device holding the sweat collector tubing may be marked toidentify the range of volume of sweat collected in the sweat collectortubing which will provide a sufficient minimum sample of sweat for sweattesting when taking into account the potential variations in theextruded cross sectional area of such tubing.

Typically, a volume of about eight or more microliters of sweat isrequired for analysis by titration or electrical conductivity methods.However, it is desirable to collect an excess of sweat for case inhandling and to allow the analysis to be repeated so as to average outany deviation in salt concentration caused either by variations in theamount of salt contained in various portions of the excreted sweat or byexternal factors. Further, it is important that the sweat collected isexcreted by the body at a minimum rate to provide reliable cysticfibrosis diagnostic results under Cystic Fibrosis Foundation guidelines.Under current Cystic Fibrosis Foundation guidelines this rate is atleast 1 gm/m²/min. This minimum collection rate will produce fifteenmicroliters of sweat in thirty minutes for a collection area of five cm²and proportionately more or less for larger or smaller collection areas.

In order to ensure enough sweat is obtained and that it is obtained atleast at the minimum rate, it is advantageous to provide an indicationwhen a minimum desirable volume of sweat, such as, for example, fifteenmicroliters of sweat, has been obtained in the sweat collector tubing.As indicated, the inside diameter of the sweat collector tubing, whichis usually formed by extrusion, is subject to small variations withinthe manufacturing tolerance for the tubing so the volume of sweatcollected within a fixed length of the tubing is subject to smallvariations (the volume of sweat collected is determined by the area ofthe inside collector tubing passage, determined by the inside diameterof the tubing, times the length of the tubing containing sweat).However, the tolerance of the inside diameter of the tubing is usuallyknown. Therefore, using the minimum inside diameter that might bepresent within the manufacturing tolerance of the tubing, the maximumlength for the minimum desired volume of sweat to be collected in thetubing can be determined, and marked, for example, mark 30 on thecollector tubing 17 in FIG. 5. When sweat has been collected to thismark 30 indicating collection to maximum length of tubing necessary toprovide the minimum desired volume of sweat, it is ensured thatregardless of the variation of the diameter of the tubing withinmanufacturing tolerances, the minimum desired volume of sweat has beencollected and collection can stop. The maximum inside diameter of thesweat collector tube that might be present within the manufacturingtolerance of the tubing will provide the minimum length for a set volumeof sweat to be collected in the tubing, such as the minimum desiredvolume of sweat, and can be determined, and marked, for example mark 31on the tubing 17 in FIG. 5. This will provide two markings, such asmarkings 30 and 31, along sweat-collector tubing 17 as shown in FIG. 5.If the sweat collected has not reached the minimum length indicated bymark 31, the minimum volume of sweat has definitely not been collected.If the sweat collected in the tubing is between the marks 30 and 31, theminimum volume of sweat may have been collected depending upon theinside diameter of the collector tube. Further measurement of the volumeof sweat is necessary to determine the actual volume of sweat collected.

As indicated, a maximum sweat collecting time is usually observed duringmost sweat collecting procedures, such as a maximum sweat collectingtime of thirty minutes. This maximum time is usually determined by theminimum amount of sweat that has to be collected, the time required atthe minimum sweat excretion rate to obtain the minimum amount of sweat,and the maximum time that induced sweating will usually produce at leastthe minimum desired rate of sweating. For example, if the maximum sweatcollecting time is thirty minutes, and during that time sweating at theminimum rate of 1 gm/m²/min will produce a volume of collected sweat inthe tubing of fifteen microliters, mark 31 on tubing 17 in FIG. 5 may bepositioned to represent a collected volume of sweat of fifteenmicroliters if the inside diameter of the tubing is at maximum allowabletolerance and mark 30 may be positioned to represent a collected volumeof sweat of fifteen microliters if the inside diameter of the tubing isat minimum allowable tolerance. During use of the device to collectsweat, the concave face of sweat-collecting portion 10 of the device isplaced and held firmly against the pilocarpine-treated surface of thepatient's skin, such as by size-adjustable strap 16. Timing of the sweatcollecting period is immediately started. The progression of the sweatcollection can be watched as the leading edge of the collected sweatmoves along the sweat-collector tubing. With the marks 30 and 31positioned as in the manner described above, if the collected sweatmoves beyond the mark 30 within the sweat collecting period, it is knownthat enough sweat has been collected at greater than the minimumcollection rate and sweat collection can be stopped at any time. As longas the sweat collected reaches mark 30 within the sweat collectingperiod, it is know that enough sweat has been collected at the minimumexcretion rate. If the collected sweat has not reached mark 31 withinthe sweat collecting period, it is known that the desired amount ofsweat has not been collected and that sweating has not been maintainedat the minimum rate during the collection period. In such case, it isgenerally necessary to redo the sweat collection procedure to providethe necessary amount of sweat for acceptable cystic fibrosis testing. Ifthe collected sweat is between marks 30 and 31, it is not known whetheror not a sufficient amount of sweat has been collected and thedetermination of the actual amount of sweat collected, which isgenerally measured as part of the testing procedure, will determinewhether enough sweat was obtained or whether the sweat collectionprocedure has to be redone.

Rather than providing the marks 30 and 31 on the sweat-collecting tubingitself, marks may be provided on the device casing in any location wherethe desired indication of amount of sweat collected can be determined.For example, marks 32 and 33 may be provided on the back of the backportion 11 adjacent the circular chamber 19 as shown in FIG. 6 toprovide a similar indication as marks on the tubing would provide. Inthe case of marks 32 and 33 in FIG. 6, which shows the same tubingarrangement as shown in FIG. 5, a user would know that the marks 32 and33 apply to the position of the leading edge of the sweat in the next tothe last coil of the tubing coil.

Alternately, where a cover is provided for the chamber 19, such cover 36being shown in FIGS. 3 and 7, markings 38 and 39, FIG. 7, can beprovided on cover 36 over the position of coiled collector tubing 17 tomark the positions similarly as they are shown on the tubing in FIG. 5.With markings 38 and 39 on cover 36, the cover can include a slot, notshown, to interface with tab 42 on back portion 11 so that cover 36 canonly be mounted on back portion 11 in one orientation to ensure that themarkings 38 and 39 are properly positioned in relation to the coiledsweat collector tubing 17.

With any of the markings described, a red area or other marking can beincluded between the minimum and maximum marks to remind a used thatwhen the sweat collection ends between those marks, further measurementof the volume of sweat collected is necessary to determine if theminimum volume of sweat has actually been collected.

Once the sweat has been collected in sweat collector tubing 17, thecollected sweat has to be removed from the tubing and discharged formeasuring a volume for testing and for actual testing of chloride,sodium, and/or total electrolyte content. Generally, in order to removethe sweat from collector tubing 17, collector tubing 17 is disconnectedfrom axial bore 18, either by pulling it free or by severing it at itsemergence from such bore. It should be noted that there is a tendencyfor a vacuum to form between the sweat collecting surface 15 and theskin, so, if the strap 16 is loosened and the device removed with tubing17 still connected, sweat may be inadvertently withdrawn from thecollector tubing and deposited back on the skin. Thus, it is importantthat the tubing 17 be removed first.

The sweat collected in flexible collector tubing 17 may be expelled orwithdrawn and tested in any convenient way. In a commonly used way ofexpelling the sweat from the sweat collector tubing of the device ofreferenced U.S. Pat. No. 4,542,751, a small syringe or blunt hypodermicneedle is inserted into the open end 44 of the sweat collector tubing 17and the tubing 17 is then cut where it connects to axial bore 18. Asindicated, this is done prior to removing the device from the skin toprevent suction that may be created during removal of the device fromthe skin from drawing sweat out of the sweat collector tubing. The sweatcan then be forced from the tubing for measurement and testing. It hasbeen found difficult with the device of referenced U.S. Pat. No.4,542,751 for some users to be able to insert the small syringe or bluntneedle into the open end 44 of the sweat collector tubing 17. Thecurrent invention can provide a flared open end 46, FIG. 8, to allow thesmall syringe or blunt needle to be more easily inserted into the flaredopen end 46 of sweat collector tubing 17. Alternatively, as shown inFIG. 9, the open end of the sweat collector tubing 17 can be providedwith a flared insert 48 or other fitting to allow the small syringe orblunt needle to be more easily inserted into or otherwise connected tothe free end 48 of sweat-collector tubing 17.

In a further embodiment shown in FIG. 10, a guide passage 50 is providedin sweat collector body 9 extending through the body from the sweatcollector tubing receiving chamber 19 to outside the sweat collectorbody 9 to guide insertion of a small syringe or blunt needle into theopen end 44 of the sweat collector tubing 17. With such arrangement, theend 44 of sweat collector tubing 17 is positioned in sweat collectortubing receiving end 52 of the guide passage 50 with the opposite, guideend 54 of the guide passage 50 opening to the outside of the collectorbody 9. The guide end 54 can be tapered, as shown. The end of a sweatcollecting needle 56, such as a small syringe or blunt needle, can beeasily inserted into the guide end 54 of guide passage 50, particularlyif the guide end is tapered, and easily pushed through the guide passage50 into the open end 44 of tubing 17, which is held in sweat collectortubing receiving end 52 of the guide passage 50. The guide passage canbe an open passage as shown, or can be a closed passage. The use of anopen passage allows easier insertion and removal of the sweat collectortubing. Again, when sweat collecting needle 56 has been inserted intothe end 44 of tubing 17, the tubing should be cut where it connects toaxial bore 18 to allow sweat collector tubing 17 to be removed fromreceiving chamber 19 and the sweat in sweat collector tubing 17 to beremoved from the tubing. While FIG. 10 shows a slightly different shapefor collector body 9 than shown in the earlier Figs., this merelyillustrates that various body shapes can be used for the device. Theparticular body shape of FIG. 10 is not necessary for use of theillustrated guide passage.

A satisfactory procedure for removal of the sweat from sweat collectortubing 17 when using the guide passage is that once the sweat has beencollected in tubing 17, if a protective cover 36 is in place over thereceiving chamber 19, remove the protective cover. Insert the sweatcollecting needle 56 into tapered end 54 of guide passage 50 and throughguide passage 50 into the open end 44 of the sweat collector tubing 17.Guide passage 50 helps in registering the needle correctly with theinside of sweat collector tubing 17. If the sweat hasn't reached theopen end 44 of the sweat collector tubing 17 where the needle isinserted, the sweat can be drawn slightly back so that the column ofsweat is in the middle of the coiled sweat collector tubing 17 with anair gap at the outer and inner ends. Lift the sweat collector tubing end44 with the needle (this requires an open guide passage as illustrated)and uncoil the tubing from the collector chamber 19. Clip or cut thetubing near where it extends from the axial bore 18 of the collectorbody 9. Transfer the sweat sample from the sweat collector tubing 17 toa sealable container for transfer to the testing site, or transfer thesweat sample directly to sweat testing apparatus when such sweat testingapparatus is immediately available for use.

While the guide passage feature of FIG. 10, the flared open tubing endfeatures of FIGS. 8 and 9, and the inclusion of markings indicatingvolume of sweat collected in the sweat collector tubing as shown inFIGS. 5, 6, and 7 are all shown in this application in connection withthe elongated sweat-collecting surface, such features can be used withthe prior art sweat collectors as well.

A further embodiment of the device of the invention is shown in FIGS. 11and 12. In the embodiment as shown in FIGS. 11 and 12, an ellipticalsweat collecting portion 60 projects from backing plate 62 whichincludes slots 64 in opposite backing plate side portions 66. Backingplate 62 includes outside perimeter edges 68 on opposite sides of theelongate axis of the elliptical sweat collecting portion 60 which areshown as substantially parallel with the slots 64 and the longitudinalaxis of the sweat collecting portion. Projections 70 extend outwardlyfrom the opposite outside perimeter edges 68. The projection 70 on eachside of the backing plate 62 is considered and described as being theprojection associated with the slot near that edge such as shown in FIG.12. Thus, FIG. 12 shows a slot and a projection associated with theslot. In the embodiment shown, the projections include a neck portion 72and enlarged ball portion 74, FIG. 12. The device is attached to apatient body portion such as an arm or leg, shown in broken lines inFIG. 11 as arm 76, by a stretchable attachment strap 78. Strap 78 may bemade of an elastic material, such as a non latex elastic material toavoid allergic reactions with the skin of the limb to which it isattached, although other stretchable materials can be used, and includesa plurality of holes 80 in each end portion 82 thereof. The end portions82 of the strap 78 are passed through respective opposite slots 64 andstretched so that a selected hole 80 in each end portion 82 can bepositioned over a projection 70. With the particular projections 70shown, ball portion 74 is passed through a selected hole 80, stretchingthe hole as it goes through. In this way, the strap 78 is attached toprojection 70 with the neck 72 passing through the hole and ball 74keeping the strap attached to the projection until it is manuallyremoved from projection 70 by the user pulling the strap to stretch thehole again as it is pulled over ball 74 from the projection 70. By usinga stretchable strap and being able to select the holes through which theprojections extend, it is possible to achieve a desired tightness of thedevice against the skin and to better equalize the pressure on each sideof the device against the body. While three holes are shown on the endportion of the strap in FIG. 11, more holes closer together willgenerally be provided to provide more adjustability to the attachmentpressure of the device.

Also as shown in FIG. 11, with the particular embodiment shown, two opentop guide passages 88 are shown extending through the body from thechamber which receives and holds the flexible sweat collecting tubing tothe outside of the device. These guide passages are as described for theembodiment of FIG. 10. However, the provision of the two passages in theembodiment of FIG. 11 provides more flexibility in being able to adjustthe length of the sweat collecting tubing so that the open end of thesweat collecting tubing will fit into the tubing receiving opening ofthe guide passage. FIG. 11 also shows a cover 90 over the chamber whichreceives and holds the flexible sweat collecting tubing.

While the foregoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

The invention claimed is:
 1. A sweat-collection device for applicationto a substantially flat area of the human body, comprising: a solid bodyhaving a face thereof forming a concave sweat-collecting surface whichgradually recedes from a rim lying wholly in a common plane to an axialbore that extends to the opposite face of said solid body, the maximumdepth of said concave sweat-collecting surface being such that the skinand flesh of said flat area of a human body to which the device isapplied will bulge into contact with said sweat-collecting surface oversubstantially the entire area thereof when said rim is placed firmlyagainst the skin of said flat area of the human body, leavingsubstantially no dead space in the interface between the bulged skin andsaid sweat-collecting surface, whereby body secretion pressure of sweatwill force said sweat through said interface to said axial bore, saidaxial bore being adapted to connect with a length of flexible, sweatcollector tubing at said opposite face of the solid body, and said solidbody being adapted to be fastened against the said flat area of a humanbody so as to maintain firm placement of said rim and sweat-collectingsurface against the skin, the opposite face of the solid body beingrecessed to form a chamber for receiving flexible sweat collector tubinghaving opposite ends when one of the opposite ends of the flexible sweatcollector tubing is connected to the axial bore and the flexible sweatcollector tubing is coiled in flat formation in the chamber with theother opposite end open so that as sweat is collected by the sweatcollecting device and flows into and through the axial bore, the sweatflows into and collects in the collector tubing, the advancement of thecollected sweat being visible as it advances in the collector tubingfrom the bore toward the open end; a guide passage extending through thesolid body from the chamber to outside the solid body, said guidepassage having a flexible sweat collector tubing receiving end adjoiningthe chamber adapted to receive and hold an open end of the sweatcollector tubing when sweat collector tubing is coiled and received inthe chamber, and a guide end opening to outside the solid body, saidguide end adapted to receive a sweat collecting needle to be guided bythe guide passage into the open end of the sweat collector tubingreceived in the sweat collector tubing receiving end of the guidepassage; and a second guide passage extending through the solid bodyfrom the chamber to outside the solid body, said second guide passagehaving a flexible sweat collector tubing receiving end adjoining thechamber adapted to receive and hold an open end of the sweat collectortubing when sweat collector tubing is coiled and received in the chamberand a guide end opening to outside the solid body, said guide endadapted to receive a sweat collecting needle to be guided by the guidepassage into the open end of the sweat collector tubing received in thesweat collector tubing receiving end of the guide passage; and wherein,depending upon the length of the sweat collector tubing when sweatcollector tubing is coiled and received in the chamber, the open end ofthe sweat collector tubing when sweat collector tubing is coiled andreceived in the chamber can be received and held in either the guidepassage or the second guide passage.
 2. A sweat-collection device forapplication to a substantially flat area of the human body in accordancewith claim 1, wherein the solid body includes a portion forming theconcave sweat-collecting surface which projects from a portion formed asa backing plate, said backing plate portion having opposite sidesextending beyond the portion forming the concave sweat-collectingsurface, said opposite sides having slots therethrough for removablyreceiving an attachment strap; and a projection associated with eachslot and extending from the backing plate portion, each projectionpositioned to extend through a hole through an end of an attachmentstrap when an end of an attachment strap is passed through the slot tothereby fasten the solid body against the said flat area to maintain thefirm placement of said rim and sweat-collecting surface against theskin.
 3. A sweat-collection device in accordance with claim 2, whereinthe backing plate includes outside perimeter edges on opposite sides ofan elongate axis and wherein the projection associated with each slotextends outwardly from respective opposite outside perimeter edges ofthe backing plate.
 4. A sweat-collection device in accordance with claim3, wherein each slot and associated projection are arranged so that anend of the strap after passing through a respective slot is doubled backover the respective outside perimeter edge of the backing plate andpositioned so that the projection projecting outwardly from therespective outside perimeter edge of the backing plate extends throughthe hole through the strap to attach the strap to the device.
 5. Asweat-collection device in accordance with claim 4, additionallyincluding a stretchable attachment strap having a plurality of holes inopposite end portions thereof with said strap being adapted to bepositioned so that a respective projection extends through a selectedone of the holes at each end of the strap to thereby adjustably attachthe strap to the device.
 6. A sweat-collection device in accordance withclaim 1, wherein the guide end of each of the guide passage and thesecond guide passage is tapered.
 7. A sweat-collection device forapplication to a substantially flat area of the human body, comprising:a solid body having a face thereof forming an elongate concavesweat-collecting surface which gradually recedes from a rim forming asmoothly curved circumference for the elongate concave sweat-collectingsurface lying wholly in a common plane to an axial bore that extends tothe opposite face of said solid body, the maximum depth of said concavesweat collecting surface being such that the skin and flesh of said flatarea of a human body to which the device is applied will bulge intocontact with said sweat-collecting surface over substantially the entirearea thereof when said rim is placed firmly against the skin of saidflat area of the human body, leaving substantially no dead space in theinterface between the bulged skin and said sweat-collecting surface,whereby body secretion pressure of sweat will force said sweat throughsaid interface to said axial bore, said axial bore being adapted toconnect with a length of flexible, sweat collector tubing at saidopposite face of the solid body, and said solid body being adapted to befastened against the said flat area of a human body so as to maintainfirm placement of said rim and sweat-collecting surface against theskin, the opposite face of the solid body being recessed as a receivingchamber for receiving flexible sweat collector tubing when connected tothe axial bore and coiled in flat formation; a length of flexible sweatcollector tubing having opposite ends and normally connected at one endto the axial bore for collecting sweat therefrom and normally coiled ina flat, spiral formation within the receiving chamber, said opposite endbeing open, whereby, as sweat is collected by the sweat collectingdevice and flows into and through the axial bore, the sweat flows intoand collects in the sweat collector tubing, the advancement of thecollected sweat being visible as it advances in the sweat collectortubing from the axial bore toward the open end; a guide passageextending through the solid body from the chamber to outside the solidbody, said guide passage having a flexible sweat collector tubingreceiving end adjoining the chamber adapted to receive and hold an openend of the sweat collector tubing when sweat collector tubing is coiledand received in the chamber and a guide end opening to outside the solidbody, said guide end adapted to receive a sweat collecting needle to beguided by the guide passage into the open end of the sweat collectortubing received in the sweat collector tubing receiving end of the guidepassage; a second guide passage extending through the solid body fromthe chamber to outside the solid body, said second guide passage havinga flexible sweat collector tubing receiving end adjoining the chamberadapted to receive and hold an open end of the sweat collector tubingwhen sweat collector tubing is coiled and received in the chamber and aguide end opening to outside the solid body, said guide end adapted toreceive a sweat collecting needle to be guided by the guide passage intothe open end of the sweat collector tubing received in the sweatcollector tubing receiving end of the guide passage; and wherein,depending upon the length of the sweat collector tubing when the sweatcollector tubing is coiled and received in the chamber, the open end ofthe sweat collector tubing coiled and received in the chamber can bereceived and held in either the guide passage or the second guidepassage.
 8. A sweat-collection device for application to a substantiallyflat area of the human body in accordance with claim 7, wherein thesolid body includes a portion of elongate formation having an elongateaxis which projects from a portion formed as a backing plate, saidportion of elongate formation forming the elongate concavesweat-collecting surface; and wherein there are means in or on saidbacking plate for removably receiving an attachment strap; wherein themeans in said backing plate for removably receiving an attachment strapare slots through the backing plate on opposite sides of the elongateaxis with slot axes substantially parallel to the elongate axis; andadditionally including a projection associated with each slot andextending from the backing plate portion, each projection adapted topass through a projection receiving hole in an end of an attachmentstrap when the end of an attachment strap is passed through a respectiveslot to thereby secure the end of the attachment strap to the device. 9.A sweat-collection device in accordance with claim 8, wherein thebacking plate includes outside perimeter edges on opposite sides of theelongate axis and wherein the projection associated with each slotextends outwardly from respective opposite outside perimeter edges ofthe backing plate.
 10. A sweat-collection device in accordance withclaim 9, wherein each slot and associated projection are arranged sothat an end of the strap after passing through a respective slot isdoubled back over the respective outside perimeter edge of the backingplate and positioned so that the projection projecting outwardly fromthe respective outside perimeter edge of the backing plate extendsthrough the hole through the strap to attach the strap to the device.11. A sweat-collection device in accordance with claim 10, wherein saidoutside perimeter edges on opposite sides of the elongate axis aresubstantially parallel with the elongate axis.
 12. A sweat-collectiondevice in accordance with claim 10, additionally including a stretchableattachment strap having a plurality of attachment receiving holes inopposite end portions thereof with said strap being adapted to bepositioned around a limb of a human body containing the said flat areaof the human body so that a respective projection extends through aselected one of the holes at each end of the strap to thereby adjustablyattach the strap to the device and thereby fasten the device against thesaid flat area of a human body so as to maintain firm placement of saidrim and sweat-collecting surface against the skin.
 13. Asweat-collection device in accordance with claim 7, wherein the smoothlycurved circumference for the elongate concave sweat-collecting surfaceis an ellipse.
 14. A sweat-collection device in accordance with claim13, wherein the ellipse has a major axis and a minor axis and the majoraxis is between 20 millimeters and 70millimeters, the minor axis isbetween 15 millimeters and 35 millimeters, and the ratio of the majoraxis to the minor axis is between 1.3 and
 2. 15. A sweat-collectiondevice in accordance with claim 7, wherein the guide end of each of theguide passage and the second guide passage is tapered.